This invention relates to an apparatus for cleaning soiled surfaces, particularly textile surfaces such as carpets.
One of the methods and apparatus used by the prior art to clean carpets includes a cleaning head which includes a spray nozzle that sprays a dilute, hot (i.e. 140.degree.F) detergent solution on the surface of a carpet and a single vacuum slot positioned in front of the spray nozzle to remove the detergent solution from the carpet. Because of the construction of the cleaning head, the head can be used to clean carpets only when the cleaning head is being pulled backwards toward the operator.
This prior art apparatus is often referred to as a "steam cleaning" apparatus although steam, in the true sense, is not used in the process. These "steam" cleaning apparatus are extremely heavy and require two men to efficiently operate them. They apply large amounts of water (6-12 gals/100 ft.sup.2) to remove all the soil from a carpet simultaneously and as a consequence, often have power requirements which exceed the normal 15 amp circuits found in a residential home. In addition, because large amounts of water which must be used in the cleaning operation, and because the single vacuum slot cannot effectively remove all the water the carpets are typically out of service for long periods of time (12-48 hours, longer in humid weather).
These steam cleaning processes work on the principle of removing soil from the carpet by liquidizing all of the soil initially present and catching and removing the liquidized soil in a high velocity air stream. These processes do not create noticeable suds or foam on the surface of the carpet since those skilled in the art have believed that suds or foam interfere with efficient removal of the liquidized soil and the water applied to the carpet by vacuum method. These processes, moreover, do not appreciably restore the texture of the carpet (i.e. relieve crushing and matting of piled) or remove surface debris and deep down dry dirt embedded near the base of the pile. As a consequence, additional cleaning steps are needed to restore the carpet to its original beauty and cleanliness so as to achieve a commercially acceptable cleaning job.
Another method often used to clean carpets is the shampoo method. In this method, a very dense, thick, nonflowing foam of the consistency of aerosal shaving foams is generated and applied to the surface of the carpet. This foam is worked into the carpet by a revolving brush. This method is effective in removing soil at surface level but often fails to remove deep down embedded dirt at the bottom of the carpet pile. In addition, if excess foam is applied to the carpet, streaking often occurs. Often these shampoo methods using a thick foam, are utilized in conjunction with an apparatus that also vacuums the carpet to take up the thick foam in addition to working the carpet with a revolving brush. While this method removes some loose, dry dirt near the base of the carpet pile, it fails to remove soil attached to the carpet fibers near the base of the pile since in practice the foam does not penetrate to the base of the pile. In addition, large amounts of a defoamer must be added to the vacuum system to break up the thick shaving cream like foam and to prevent temporary occulsion or plugging in the vacuum lines and overflowing of the soil receivers.